Appliances for the detection of sharp shooter or snipers are known, which are based on the so-called cat's eye effect, with retroreflected light from the optical appliances or systems of the gunners being detected. If the optical system is a telescopic sight, the radiation is reflected, for example, from the reticle, in the same direction from which the illuminating radiation came. A laser beam at an appropriate wavelength is generally used for active illumination of the optics to be detected, for this purpose. Visual light is generally not used for illumination since, on the one hand, eye safety with laser light in the visual band is not ensured and, on the other hand, the visual light can itself be easily detected. Inter alia, optics such as telescopic sights, telescopes, periscopes or thermal imagers, can be recorded. Two technical solutions are essentially known in this case.                1. The transmitted laser beam is detected using a camera which is sensitive for radiation in the appropriate wavelength range of the laser. This is generally the SWIR band, so that an SWIR camera is likewise used in order to record the retroreflection of the laser. Cameras such as these record only the retroreflection of the laser, and not the entire surrounding area, however, when it is dark. External illumination is therefore required, as well as a further camera (for example a thermal imager) to make the surrounding area visible. The user is therefore displayed a superimposition of the images of the two cameras.        2. In the case of purely optical systems, the display is provided just by illumination of a light-emitting diode, which appears aligned with the target to be detected.        
WO 03/102626 A discloses an apparatus for identification of optical and optoelectronic objects. The apparatus uses a laser light source with a light outlet which is widened one-dimensionally in the vertical direction and is aimed at a target area. A row of detectors arranged vertically one above the other receives the light reflected from the target area. Furthermore, a telescope-like optical observation system is provided.
The prior DE 10 2005 006 726, which was not published prior to this, discloses a method and an apparatus for detection of optical systems, for example of gunners in a terrain area. The terrain area is optically scanned by means of a moving mirror, and the position of the gunner is determined from a measurement, which is carried out by means of a laser arrangement, and is displayed visually. The position of the gunner is determined directly from the measurement (which is carried out by means of the laser arrangement) by evaluation of the intensity of a laser beam, which is reflected from an optical surface of the gunner, of the laser arrangement, and is injected into a telescope. The apparatus has a laser arrangement containing a moving mirror, a controller for determination of the position of the gunner, as well as an apparatus for visual display of the position. In this case, the visual display apparatus is a telescope, and means are provided for injection of the position of the gunner into the telescope.